Biology subjects

Reby, D.

Publications and source records attributed to Reby, D..

3 recordsLinked to original sources

bioRxiv2026

Vocal Signatures of Stress Relief: Effects of Appeasing Harness and Synthetic Pheromone on Puppy Whine Acoustics in Separation Context (Canis familiaris)

In mammals, loud, high-pitched, and harsh-sounding calls typically accompany heightened emotional arousal, particularly during distress such as separation. However, whether subtle arousal reductions can be detected through acoustic analysis within a single negative context remains unclear. We investigated whether source-related acoustic parameters of puppy whines reflect arousal modulations induced by calming interventions during maternal separation. Thirty-five eight-week-old Beagle puppies were recorded under four conditions combining synthetic appeasing pheromone and a pressure harness. Vocal behavior, activity, whine duration, and intensity, did not significantly differ across treatments, suggesting interventions did not suppress separation-related vocal responses. Nevertheless, calming products selectively altered acoustic parameters known to index arousal in dog vocalizations. Puppies receiving combined treatments produced whines with lower fundamental frequency (fo) and reduced fo variability, while pheromone exposure increased call tonality, reflected by reduced jitter and shimmer and elevated harmonics-to-noise ratios. Spectral entropy remained unchanged, possibly because the proportion of whines containing nonlinear phenomena did not vary across conditions. Reductions in fo, fo variability, and acoustic roughness are consistent with established correlates of lower arousal in mammals, suggesting source-related vocal parameters sensitively capture subtle arousal shifts even when overt vocal behavior remains stable, supporting their use as bioacoustic indicators for evaluating welfare interventions.

animal behavior and cognition↗

bioRxiv2026

Acoustic remote sensing with deep learning enables non-invasive estimation of seabird nest density

Passive Acoustic Monitoring (PAM) has advanced ecological research by enabling non-invasive recordings of wildlife vocalizations that provide insight into species presence, behavior, and reproductive activity. This remote-sensing approach is particularly valuable for species breeding in concealed habitats or remote areas where visual surveys are challenging. The Critically Endangered African Penguin, burrow-nesting seabird, exemplifies this challenge. Its highly vocal breeding behavior makes it an ideal case study for evaluating passive acoustic monitoring as a low-disturbance approach to estimating nest density. To evaluate this, we deployed Autonomous Recording Units at multiple sampling points across the Stony Point Penguin Colony, capturing soundscapes spanning different nest densities and environmental conditions. We then developed an automated detector for Ecstatic Display Songs (EDS), the species characteristic territorial song, using a Convolutional Neural Network trained on a multi-source dataset covering several breeding seasons, diverse acoustic environments, and both in situ and ex situ recordings. The model achieved high recall and precision and remained robust across diverse environmental conditions, supporting the use of heterogeneous training datasets for reliable bioacoustics detection. Using the automated EDS detections, we then investigated how vocal activity peaks relate to local nest density. A Generalized Additive Model revealed that EDS peaks strongly predicted nest density, with a nonlinear increase that plateaued at high calling rates. Importantly, models trained in one breeding season generalized well to the next. In conclusion, by integrating PAM with deep learning, this study provides a scalable, low-disturbance framework for estimating penguin nest density from soundscape data, supporting colony rangers in monitoring penguin colonies. HighlightsO_LILarge-scale acoustic monitoring captured the soundscape of a critically endangered seabird species. C_LIO_LIDeep-learning-based acoustic detection reliably identified key breeding vocalizations in field recordings. C_LIO_LIPeak vocal activity strongly and nonlinearly predicted active nest density across sampling points. C_LIO_LIThe vocal-nest relationship increases rapidly and plateaued at high levels of vocal activity. C_LIO_LIThis approach enables scalable, low-disturbance monitoring of seabird nest density. C_LI

zoology↗

bioRxiv2024

Honestly exaggerated: howler monkey roars are reliable signals of body size and behaviourally relevant to listeners

Acoustic signals are key components of animal social behaviour, potentially conveying fitness relevant information about signallers. Howler monkeys produce extremely loud, low frequency roars, which exaggerate the acoustic impression of body size relative to other species. However, it remains unclear whether howler monkey roars contain reliable information about body size within species, and whether conspecific listeners use this information and adjust their responses accordingly. Here, we investigate whether the roars of black and gold howler monkeys (Alouatta caraya) function as an honest signal of body size by examining the relationship between formant spacing and body mass in 11 adult males. We found a strong negative correlation, indicating that larger males produce roars with lower formant spacing. To test the behavioural relevance of variation in formant spacing, we then conducted playback experiments with 23 conspecific listeners, simulating the roars of unknown males of small, average, and large body size. Listeners showed significantly different responses to calls of different body sizes, spending longer orientated towards the playback speaker and being more likely to approach calls simulating larger males. There was no significant impact of simulated body size on the likelihood of listeners vocalising in response, although males spent significantly more time vocalising in response to playbacks than females. Overall, these findings suggest that formant spacing in howler monkey roars serves as an honest indicator of body size and plays a critical role in mediating social interactions. Our study highlights the adaptive significance of acoustic cues to body size, which can provide receivers with accurate information that can be used to assess rivals or choose mates.

animal behavior and cognition↗